Heat exchanger

ABSTRACT

The invention relates to an air-air heat exchanger as a regenerator, having at least one positionally fixed or movable storage mass through which alternately outside air and exhaust air flows in order to heat or cool the supply air of air-conditioned buildings and thereby save energy during the heating or cooling of interior spaces, wherein the storage mass has plastic, in particular propylene or is composed of plastic, in particular propylene.

The invention relates to an air-air heat exchanger in the form of a regenerator, comprising at least one fixed or movable storage mass through which flows either incoming outside air or outgoing inside air in order to warm or to cool the incoming air of air-conditioned buildings, and thus save energy when heating or cooling interior spaces.

Air-air heat exchangers are known that have plate fins made of aluminum.

The material and production of these heat exchangers are costly. In addition, the material results in undesirable weight, despite the fact that aluminum is among the lightest of metals. However, high heat storage capacity can be achieved only with a high mass, and an aluminum heat exchanger, for example on the roof of large industrial buildings to be cooled results in a significant load.

The object of the invention is to provide an air-air heat exchanger that while having high heat-storage capacity and being simple to manufacture has low pressure losses and is inexpensive and of low weight.

This object is achieved according to the invention by an approach wherein the storage mass includes plastic, in particular, polypropylene, or is composed of plastic, in particular, polypropylene.

In terms of mass or weight, a heat exchanger made of plastic, in particular, polypropylene, has a higher heat storage capacity than aluminum. Given identical weight, the heat storage capacity is twice that of aluminum. The density of polypropylene is only approximately one third that of aluminum, with the result that although polypropylene requires a greater volume for the same performance it nevertheless also creates a larger surface for absorbing and transferring heat energy.

Aside from the lower weight, polypropylene for heat exchangers has the essential advantage of freedom from corrosion, and also of allowing a wide variety of storage mass structures to be produced easily and inexpensively.

An approach is preferably proposed where the storage mass is assembled from two parallel spaced plastic plate fins, in particular, polypropylene plate fins defining intermediate spaces through which the air flows. The plastic can also be composed of corrugated sheets, twin-walled sheets, and/or double-web sheets. At least every second polypropylene plate fin can be corrugated.

An approach is also proposed where the plastic plate fins, in particular, polypropylene plate fins and/or plastic/poly-propylene corrugated material has a thickness of 0.1 to 0.3 mm. The plate fins here, and/or the plastic/polypropylene corrugated material, can have a thickness of 0.15 mm. An approach is furthermore proposed where the corrugation height is 2 to 4 mm. The corrugation height can preferably be 3 mm.

In a preferred embodiment, two fixed plastic/polypropylene storage masses are provided parallel to each other acting as two accumulators, through which the outside air and the outgoing air can be alternately transported. Each accumulator here includes two or more storage packets composed of plastic/polypropylene plate fins.

Embodiments of the invention are described in detail below.

The air-air heat exchanger (regenerator) includes at least one storage mass composed of plastic, in particular, polypropylene as the heat storage accumulator through which warm and cold air alternately flow. The storage mass is fixed or can move in the case of a rotary heat exchanger.

In a preferred embodiment, two fixed heat exchangers are provided parallel to each other, each including two or more storage masses (accumulators) through which warm and cold air alternately flow. During a short time span of 20 to 60 seconds, in particular, 40 second, warm exhaust air from a building flows through the first heat exchanger and is warmed, while cool outside air flows through the second heat exchanger, which air is warmed by the second heat exchanger in order subsequently to move as incoming air into the building. Following this, the two air flows are switched, and the first heat exchanger warms the outside air while the second heat exchanger is warmed by the exhaust air.

Both heat exchangers include at least one, preferably two or more series-connected storage masses composed of plastic, preferably of polypropylene. Each storage mass here is assembled from plastic/polypropylene plate fins that together form gap-like intermediate spaces between which the air flows through. Each storage mass here is assembled from corrugated sheets, twin-walled sheets, and/or double-web sheets. Corrugated plastic/polypropylene plate fins preferably alternate with flat smooth plastic/polypropylene plate fins.

The material of the plate fins, and in particular of the corrugations, has a thickness of 0.1 to 0.3 mm, in particular, 0.15 mm, while the corrugation height preferably measures 3 mm.

Among the advantages achieved by this type of air-air heat exchanger are:

-   -   a reduction of approximately 48% in the weight of the storage         means     -   an increase of the effective surface of the storage means by         approximately 90% for the same heat storage capacity. 

1. An air-air heat exchanger in the form of a regenerator, comprising at least one fixed or movable storage mass through which incoming outside air and outgoing inside air flow in order to warm or to cool the incoming air of air-conditioned buildings, and thus save energy when heating or cooling interior spaces, the storage mass being formed at least partially polypropylene.
 2. The heat exchanger according to claim 1, wherein the storage mass is assembled from parallel spaced polypropylene plate fins, through the intermediate spaces of which the air flows.
 3. The heat exchanger according to claims 1, wherein the polypropylene forms corrugated sheets, twin-walled sheets, or double-web sheets.
 4. The heat exchanger according to claim 1, wherein at least every second polypropylene plate fin is of corrugated shape.
 5. The heat exchanger according to claim 2, wherein polypropylene plate fins or polypropylene corrugated material has a thickness of 0.1 mm to 0.3 mm.
 6. The heat exchanger according to claim 2, wherein the plate fins or the polypropylene corrugated material has a thickness of 0.15 mm.
 7. The heat exchanger according to claim 3, wherein the corrugation height is 2 to 4 mm.
 8. The heat exchanger according to claim 2, wherein the corrugation height is 3 mm.
 9. The heat exchanger according to claim 1, wherein two fixed polypropylene storage masses acting as two accumulators are provided parallel to each other through which incoming outside air and outgoing inside air are alternately conveyed.
 10. The heat exchanger according to claim 9, wherein each accumulator includes two or more storage packets composed of polypropylene plate fins. 